The present invention relates to a stator of a vehicle mounted alternator and, particularly, to a construction of a neutral terminal of an armature coil of a three-phase alternator.
FIG. 9 shows an electric circuit of an example of a conventional alternator of such type. In FIG. 9, reference numeral 1 depicts a three-phase alternator, 101a, 101b and 101c armature coils for respective phases whose lead terminals are represented by letters A B and C, 101n a common neutral point of the respective phases with lead terminal N and field coil 102; full-wave rectifier 2 composed of a first rectifier element 201, a second rectifier element 202 and a third rectifier element 203 for rectifying an ac output of the alternator 1; voltage regulator 3 for regulating the output of the alternator 1 by switching field current of the field coil 102; battery 4, electric load 5, switch 6 for the load, key switch 7 and battery charge indicator 8.
FIGS. 10 to 12 show an example of the conventional alternator structure, in which a reference numeral 9 depicts a rotary shaft to be driven by an engine (not shown) and 10 a field core fixedly mounted on the rotary shaft 9 on which the field coil 102 is mounted. Cylindrical mold member 11 is fitted on the rotary shaft 9, in an outer periphery of which a pair of slip-rings 12 are fixedly supported. The slip-rings 12 are connected electrically to opposite ends of the field coil 102. Annular armature core 13 is arranged in an opposing relation to the field core 10 with an annular radial gap therebetween. The annular armature core 13 is formed on an outer periphery thereof with a plurality of slots 13a in which armature coils 101a, 101b and 101c are arranged. Bearings 14 are for the rotary shaft 9, brackets 15 for supporting the rotary shaft 9 through the bearings 14 and a brush holder 16 is integrally formed with the voltage regulator 3 and mounted on the brackets 15. Cooling fin 17 is on a positive side of the full-wave rectifier 2 and cooling fin 18 on a negative side of the rectifier in an opposing relation to the cooling fin 18 radially. Positive terminal plates of the first and the second rectifier elements 201 and 202 of each phase and negative terminal plates thereof are soldered to the cooling fins 17 and 18, respectively.
The first and the second rectifier elements 201 and 202 are arranged opposingly between the cooling fins 17 and 18 and their lead wires 201a and 202a from terminals fixed thereto are derived in the same direction. By soldering the lead terminals A, B, C and N of the armature colis 101a, 101b, 101c and the neutral point to the terminal lead portions of the first and the second rectifier elements of each phase, wirings of the first and the second rectifier elements 201 and 202 and the coils 101a, 101b and 101c of the armature are compeleted simultaneously.
Although the third rectifier element 203 is arranged between the cooling fins 17 and 18 and connected to the lead terminals A, B and C, details thereof are omitted in this description since it is out of the scope of this invention. The positive side cooling fin 17 is electrically isolated from the negative side cooling fin 18 by an insulating material 19, as shown in FIG. 12.
The fullwave rectifier 2 constituted as above is secured by a screw 21 through an insulating material 20 and an output terminal bolt 22 with a nut 23 through an insulating material 23 to the bracket 15.
In FIGS. 13 to 20 which show a rotor, i.e., an armature of a conventional vehicle mounted alternator, reference numeral 31 depicts a coil unit formed by winding coils 30 circularly the number of turns being necessary for a phase, e.g., 6 turns, 32 a coil member formed by shaping the coil unit 31 into a gear shape by a shaper (not shown). Two of these coil members 32 are assigned to each phase and thus six of them are required for three phases. 32A and 32N depict lead terminals of the coil member 32 in which 32N is a lead terminal of a neutral point. 33 depicts a stator obtained by inserting the coil member 32 into slots 13a of the armature core 13, 34 coil ends, 35 a wedge inserted into each of the slots 13a, 36 a protective tube for a junction of three neutral leads 32N of each phase and 37 a lead portion formed by neutral leads from the respective protective tubes 36 and forming the neutral lead terminal N.
In manufacturing the armature mentioned above, the coil unit 31 is first formed by winding coils 30 the requisite times for one phase. Then the coil unit 31 is shaped by the shaper into the gear configuration to form the coil member 32. Two of the coil members 32 are paired and combined such that lands of one coil member 32 oppose valleys of the other as shown in FIG. 17 and inserted into the slots 13a of the armature core 13, sequentially, as shown in FIG. 18. In FIG. 20, the circled numerals .circle.1 - .circle.6 represent various coils 32 as shown in FIG. 20, coil members .circle.1 and .circle.4 , .circle.2 and .circle.5 and .circle.3 and .circle.6 are paired respectively and they are inserted into the 36 slots 13a of the armature 13 in the order of .circle.1 , .circle.4 , .circle.2 , .circle.5 , .circle.3 and .circle.6 . Thereafter, three neutral leads 32N of the respective coil members (1), (4) and (2) are connected together by soldering, from which the lead portion 37 extends through the coil end 34 to a position between the lead terminals B and C of the respective phases. Three neutral leads 32N of the coil member .circle.5 , .circle.3 and .circle.6 are connected together by soldering, from which a lead portion 37 is derived and positioned similarly. These two lead portions 37 constitute the neutral lead terminal N. Note, in FIG. 20, the lead terminals A, B and C, respectively, are denoted by ovals.
In the stator of the conventional vehicle mounted alternator constructed as mentioned above, the neutral lead terminals 32N of the armature coils 101a, 101b and 101c of the respective phases are angularly separated from each other by 100.degree. peripherally of the armature core 13. The vertical lines in FIG. 20 represent 10.degree. increments on the periphery of the armature. Therefore, it is necessary to twist and solder three of the neutral leads 32N for each phase. Further, it is necessary to provide the insulating tube 36 on each of the soldered portions. Also the lead portion 37 must be directed through the insulating tube and passed through the coil end 34 so that the position of an end portion thereof is maintained stably. Thus, the formation of the lead terminal N of the conventional armature requires a number of manual operations, causing automatic assembling to be impossible. Further, the neutral leads 32N of the armature coils 101a, 101b and 101c of each phase must be extended peripherally, and relatively long lead portions 37 must be provided. Therefore, the vibration-resistivily of the armature is low, resulting in a degradation of insulation of the respective coils.